1、 INTERNATIONAL TELECOMMUNICATION UNION CCITT M.300THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE (11/1988) SERIES M: GENERAL MAINTENANCE PRINCIPLES Maintenance of international transmission systems and telephone circuits International transmission systems DEFINITIONS CONCERNING INT
2、ERNATIONAL TRANSMISSION SYSTEMS Reedition of CCITT Recommendation M.300 published in the Blue Book, Fascicle IV.1 (1988) NOTES 1 CCITT Recommendation M.300 was published in Fascicle IV.1 of the Blue Book. This file is an extract from the Blue Book. While the presentation and layout of the text might
3、 be slightly different from the Blue Book version, the contents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below). 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administrat
4、ion and a recognized operating agency. ITU 1988, 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Fascicle IV.1 Rec. M.300 1 Recommendation M.300 DEFINITIONS CONCERNING INTERNATIONAL TRANSMISSION SYSTEMS 1
5、Definitions concerning international analogue transmission systems Note 1 This Recommendation is partly duplicated in Recommendation G.211 1. Note 2 Figure 1/M.300 refers to definitions 1.2 to 1.13. Figures 2/M.300, 3/M.300 and 4/M.300 refer to definitions 1.1 to 1.18. Those of the following definit
6、ions that concern links or sections apply, unless otherwise stated, to the combination of both directions of transmission. A distinction between the two directions of transmission may, however, be necessary in the case of unidirectional, multiple-destination links or sections set up over multiple-de
7、stination communication satellite systems. 1.1 line link (using symmetric pairs, coaxial pairs, radio-relay link, etc.) A transmission path, however provided, together with all the associated equipment, such that the bandwidth available, while not having any specific limits, is effectively the same
8、throughout the length of the link. Within the link there are no direct filtration points nor any through-connection points for groups, supergroups, etc., and the ends of the link are the points at which the band of line frequencies is changed in some way or other. 1.2 group section The whole of the
9、means of transmission using a frequency band of specified width (48 kHz) connecting two consecutive group distribution frames (or equivalent points). 1.3 group link The whole of the means of transmission using a frequency band of specified width (48 kHz) connecting two terminal equipments, for examp
10、le, channel translating equipments, wideband sending and receiving equipments (modems, etc.). The ends of the link are the points on group distribution frames (or their equivalent) to which the terminal equipments are connected. It can include one or more group sections. 1.4 group A group consists o
11、f a group link connected at each end to terminal equipments. These terminal equipments provide for the setting-up of a number of telephony channels (generally 12), one or more data transmission or facsimile channels, etc. It occupies a 48 kHz frequency band. Figures 1/M.320, 2/M.320 and 3/M.320 show
12、 various possible arrangements of telephony channels in a basic group B (60 to 108 kHz). 1.5 supergroup section The whole of the means of transmission using a frequency band of specified width (240 kHz) connecting two consecutive supergroup distribution frames (or equivalent points). 1.6 supergroup
13、link The whole of the means of transmission using a frequency band of specified width (240 kHz) connecting two terminal equipments, for example, group translating equipments, wideband sending and receiving equipments (modem, etc.). The ends of the link are the points on supergroup distribution frame
14、s (or their equivalent) to which the terminal equipments are connected. It can include one or more supergroup sections. 2 Fascicle IV.1 Rec. M.300 1.7 supergroup A supergroup consists of a supergroup link connected at each end to terminal equipments. These terminal equipments provide for the setting
15、-up of five group links or sections occupying adjacent frequency bands in a 240 kHz band or for one or more data transmission or facsimile channels, etc. The basic supergroup occupies the band 312 to 552 kHz. Figure 1/M.330 shows the position of groups and channels within the supergroup. 1.8 masterg
16、roup section The whole of the means of transmission using a frequency band of specified width (1232 kHz) connecting two consecutive mastergroup distribution frames (or equivalent points). 1.9 mastergroup link The whole of the means of transmission using a frequency band of specified width (1232 kHz)
17、 connecting two terminal equipments, for example, supergroup translating equipments, wideband sending and receiving equipments (modems, etc.). The ends of the link are the points on mastergroup distribution frames (or their equivalent) to which the terminal equipments are connected. It can include o
18、ne or more mastergroup sections. 1.10 mastergroup A mastergroup consists of a mastergroup link terminated at each end by terminal equipments. These terminal equipments provide for the setting-up of five supergroup links or sections occupying frequency bands separated by 8 kHz in a 1232 kHz band. The
19、 basic mastergroup consists of supergroups 4, 5, 6, 7 and 8 within the band of frequencies 812 kHz to 2044 kHz. (See Figure 1/M.340.) 1.11 supermastergroup section The whole of the means of transmission using a frequency band of specified width (3872 kHz) connecting two consecutive supermastergroup
20、distribution frames (or equivalent points). 1.12 supermastergroup link The whole of the means of transmission using a frequency band of specified width (3872 kHz) connecting two terminal equipments, for example, mastergroup translating equipments, wideband sending and receiving equipment (modems, et
21、c.). The ends of the link are the points on supermastergroup distribution frames (or their equivalent) to which the terminal equipments are connected. It can include one or more supermastergroup sections. 1.13 supermastergroup A supermastergroup consists of a supermastergroup link connected at each
22、end to terminal equipments. These terminal equipments provide for the setting-up of three mastergroup links or sections separated by two free spaces of 88 kHz and occupying a band whose total width is 3872 kHz. The basic supermastergroup is composed of mastergroups 7, 8 and 9 occupying the frequency
23、 band 8516-12 388 kHz. (See Figure 1/M.350.) 1.14 15 supergroup assembly section1The whole of the means of transmission using a frequency band of specified width (3716 kHz) connecting two consecutive 15 supergroup assembly distribution frames (or equivalent points) and connected, at least at one end
24、, to through-15 supergroup assembly connection equipment. It always forms part of a 15 supergroup assembly link. _ 1This definition is still under study by Study Group IV and is not identical to the one given in Recommendation G.211 1. Fascicle IV.1 Rec. M.300 3 1.15 15 supergroup assembly link1The
25、whole of the means of transmission using a frequency band of specified width (3716 kHz) connecting two 15 supergroup assembly distribution frames (or equivalent points). It can be made up of a number of 15 supergroup assembly sections. When terminal equipments are connected to both ends, it becomes
26、a constituent part of a 15 supergroup assembly for carrying telephony or telegraphy channels or data or facsimile, etc. 1.16 15 supergroup assembly A 15 supergroup assembly consists of a 15 supergroup assembly link terminated at each end by terminal equipments. These terminal equipments provide for
27、the setting-up of 15 supergroup links or sections separated by free spaces of 8 kHz and occupying a band whose total width is 3716 kHz. The basic 15 supergroup assembly is made up of supergroups 2 to 16 occupying the frequency band 312-4028 kHz. 1.17 through-group connection point When a group link
28、is made up of several group sections, they are connected in tandem by means of through-group filters at points called through-group connection points. 1.18 through-supergroup connection point When a supergroup link is made up of several supergroup sections, they are connected in tandem by means of t
29、hrough-supergroup filters at points called through-supergroup connection points. 1.19 through-mastergroup connection point When a mastergroup link is made up of several mastergroup sections, they are connected in tandem by means of through-mastergroup filters at points called through-mastergroup con
30、nection points. 1.20 through-supermastergroup connection point When a supermastergroup link is made up of several supermastergroup sections, they are connected in tandem by means of through-supermastergroup filters at points called through-supermastergroup connection points. 1.21 through-15 supergro
31、up assembly connection point When a 15 supergroup assembly link is made up of several 15 supergroup assembly sections, these sections are interconnected in tandem by means of through-15 supergroup assembly filters at points called through-15 supergroup assembly connection points. Note In a country n
32、ormally using mastergroup and supermastergroup arrangements, a 15 supergroup assembly can be through-connected without difficulty at the supermastergroup distribution frame by means of through-supermastergroup filters. In this case, the 15 supergroup assembly is through-connected to position 3 (8620
33、-12 336 kHz) instead of position 1 (312-4028 kHz) as required by the definition of the through-connection point of such an assembly. The point where this through-connection is made is a through-supermastergroup connection point and not a through-15 supergroup assembly connection point. 1.22 regulate
34、d line section (symmetric pairs, coaxial pairs or radio relay links) In a carrier transmission system, a line section on which the line-regulating pilot or pilots are transmitted from end to end without being subjected to any intermediate amplitude regulation associated with the pilot or pilots. _ 1
35、This definition is still under study by Study Group IV and is not identical to the one given in Recommendation G.211 1. 4 Fascicle IV.1 Rec. M.300 FIGURE 1/M.300 Group, supergroup, etc. link 2 Definitions concerning international digital transmission systems Note 1 This Recommendation is partly dupl
36、icated in Recommendation G.701 2. Note 2 Figure 5/M.300 refers to definition 2.3 below. Figure 6/M.300 refers to definitions 2.10 to 2.19 below. Those of the following definitions that concern digital paths or sections apply, unless otherwise stated, to the combination of both directions of transmis
37、sion. A distinction between the two directions of transmission may, however, be necessary in the case of unidirectional, multiple-destination paths or sections set up over multiple-destination communication satellite systems. 2.1 alarm indication signal (AIS) A signal that is used to replace the nor
38、mal traffic signal when a maintenance alarm indication has been activated. 2.2 upstream failure indication An indication provided by a digital multiplexer, line section or radio section, that a signal applied at its input port is outside its prescribed maintenance limit. 2.3 primary block (American:
39、 digroup) A basic group of PCM channels assembled by time division multiplexing. Note The following conventions could be useful: Primary block a basic group of PCM channels derived from 1544 kbit/s PCM multiplex equipment. Primary block A a basic group of PCM channels derived from 2048 kbit/s PCM mu
40、ltiplex equipment. Fascicle IV.1 Rec. M.300 5 FIGURE 2/M.300 Channel of a group set-up on: several line links in tandem (A), a single line link (B) FIGURE 3/M.300 Mastergroup link 6 Fascicle IV.1 Rec. M.300 FIGURE 4/M.300 15-supergroup assembly link 2.4 PCM multiplex equipment Equipment for deriving
41、 a single digital signal at a defined digit rate from two or more analogue channels by a combination of pulse code modulation and time division multiplexing (multiplexer) and also for carrying out the inverse function (demultiplexer). The term should be preceded by the relevant equivalent binary dig
42、it rate, e.g., 2048-kbit/s PCM multiplex equipment. 2.5 digital multiplexer Equipment for combining by time division multiplexing two or more tributary digital signals into a single composite digital signal. 2.6 muldex A contraction of multiplexer-demultiplexer. The term may be used when the multipl
43、exer and demultiplexer are associated in the same equipment. Note When used to describe an equipment, the function of the equipment should qualify the title, e.g., PCM muldex, data muldex, digital muldex. 2.7 digital multiplex equipment The combination of a digital multiplexer and a digital demultip
44、lexer at the same location. 2.8 digital multiplex hierarchy A series of digital multiplexers graded according to capability so that multiplexing at one level combines a defined number of digital signals, each having the digit rate prescribed for a lower order, into a digital signal having a prescrib
45、ed digit rate which is then available for further combination with other digital signals of the same rate in a digital multiplexer of the next higher order. 2.9 transmultiplexer An equipment that transforms frequency division multiplexed signals (such as group or supergroup) into corresponding time
46、division multiplexed signals that have the same structure as those derived from PCM multiplex equipment. The equipment also carries out the inverse function. Fascicle IV.1 Rec. M.300 7 2.10 digital distribution frame A frame at which interconnections are made between the digital outputs of equipment
47、s and the digital inputs of other equipments. 2.11 digital section The whole of the means of transmitting and receiving between two consecutive digital distribution frames (or equivalent) a digital signal of specified rate. Note 1 A digital section forms either a part or the whole of a digital path.
48、 Note 2 Where appropriate, the bit rate should qualify the title. 2.12 digital path The whole of the means of transmitting and receiving a digital signal of specified rate between those two digital distribution frames (or equivalent) at which terminal equipments or switches will be connected. Termin
49、al equipments are those at which signals at the specified bit rate originate or terminate. Note 1 A digital path comprises one or more digital sections. Note 2 Where appropriate, the bit rate should qualify the title. Note 3 Digital paths interconnected by digital switches form a digital connection. 2.13 digital line section Two consecutive line terminal equipments, their interconnecting transmission medium and the in-station cabling between them and their adjacent digital distribution frames (or e
